Piston skirt expander



Jul 25, 1939.

L. A. WITTER PISTONSKIRT EXPANDER Filed Feb. 10, 1934 B /Z r 4%?"attorneys Patented July 25, 1939 UNITED; STATES "PATENT OFFICE PISTONSKIRT EXPANDER Leon A. Witter, Parma, Ohio Application February 10,1934, Serial No. 710,658

13 Claims.

, This invention relates toexpandirig devices and more particularly toan improved device for expanding the skirt of a split skirt piston ofthe type commonly used in the internal combustion;

5 engines of automotive vehicles.

Aluminum alloy pistons having split skirts are in very extensive use. Ina common form of-this v type of piston the skirt is secured to the headpor- 20 uneven wearing of the skirt which results in an uneven bearingagainst the walls of the cylinder. When this occurs piston slap or'knocking re- Y suits, at least when the engine is cold. In order toovercome this diflicultypistons are now manu- 25 factured, the skirts ofwhich are originally ground inan oval or elliptical form so that whenthey expand upon being heated to operating temperature they become roundand thus properly fit the walls of the cylinder.

Anumber of devices have'been proposed, and

are inextensiVe use, for expanding the skirt of a piston having aslotted skirt to increase the diameter-of the skirt and make it fit thecylinder wallsafter it has been worn to such an extent .35 that knockingoccurs. The devices; of this type bodiment of my invention.

with'which I am familiar are "in the nature of expanding rings which fitinside the walls of the piston skirt and may be expanded by suitablemeans to cause an increase inthe diameter of the 40 skirt.

It is among the objects of my invention to provide means for expanding:the skirt of a slotted skirt piston wherebya worn piston may be made toproperly fit within the cylinder; Other objects '45 of rnyinvention-are:the, provision of a piston skir't expanding device which may bequickiyand easily inserted in apistonand which may be set to give anydesired degree-of expansion of the piston; the .provisionof apis'tonskirtexpanding 50 device which is of lightweight and small size andwhich does not 'interfere'with the normal opera-- tion of the piston orits associated parts; the provision of a piston skirt expanding devicewhich isadaptedto expand a worn piston and give the 55 skirt of thepiston an ellipticalshape whereby the desired operating characteristicsare obtained; the provision of a piston skirt expanding device which isadapted to expand the skirt of a piston without destroying the inherentresiliency of the slotted skirt; the provision of a piston skirtexpanding device which is particularly susceptible to economicalmanufacture, which may be readily installed and which, once installed,will notbecome dislodged while the piston is in use.

The above and-other objects of my invention will. appear from thefollowing description of several embodiments thereof, reference beinghad to, the accompanying drawing, in which Figure 1 is an enlargedperspective view of my piston skirt expanding device showing the parts;in assembled position.

' Figure 2 is a cross section taken on line 2-2 of Figure 5 and alsoshowing portions of the wall of the piston skirt to which the expandingdevice is attached- Y Figure 3 is a longitudinal cross sectional viewtaken on line 3-3 of Figure 1 and illustrating the expanding device ofFigure 1 with the parts in the positions they assume when the device isinstalled in a piston.

Figure 4 is a detached viewer the flexible slotted tapered sleevepurtionof my expander.

Figure 5 is a side elevation of a'slottedskirtpistan with one of myexpanding devices installed therein. Figure 6 is a fragmentary viewillustrating a portion of the skirt of a piston with my expand- ,ingdevice installed.

Figure '7 is a cross se tional view: similar to Figure .3 butillustrating aslightly modified-em: '36 a,

Figure 8 is a detached perspective view of the locking washerillustrated in Figurefl.

Figure 9 is a perspective view, approximately fullscale, of a modifiedform of my piston ex- 40 pander. v Y FigurelO is a :cross sectional viewgenerally 7 similar to Figure 2 but illustrating a different form ofthesleeve member.

Referring now to Figure 1, my improved ex- I panding device comprises atapered slotted sleeve i preferably made of spring sheet steel orthelike and having its edges 3 and '4 adjacent. the longitudinal slotvZturned back-to form hook shaped lipsor flanges which are adapted toengage the and length of the plug are preferably such that the large endof the plug projects out beyond the large end of the sleeve I when theinner surface of the sleeve and the outer surface of the plug are incontact. The screw 1 is adapted to have threaded engagement in the hole6 of the plug 5 and is provided with an enlarged portion,

preferably a slotted head 8, to facilitate adjust-' ment of the expanderand form a shoulder which will coact with the sleeve I to draw the plug5 into the sleeve. posed between the underside of the head 8 of thescrew and the small end of the tapered sleeve I and serves to assist inlocking the screw in ad-- justed position.

Before installing my expanding device in a piston the edges of the slotin the piston skirt are chamfered as is clearly seen in Figure 2. Anysuitable tool may be used for this purpose but, as such tool does notform part of this invention, it need not'be described here. Next theexpanding device, with the parts assembled as shown in Figure 1, isslipped upwardly into the position shown in Figure 5 with the large endof the plug 5 toward the head of the piston and with the hook shapedlips 3 and 4 engaging the edges of the slot in the piston. Preferablythe device is positioned with the center'of the tapered sleeve lyingsubstantially on a plane passing through the centers of the piston pinbearings. Next, the screw I is rotated to draw the tapered plug 5 downinto the sleeve l. that, as the plug 5 enters the sleeve I it will forcethe lips 3 and A apart increasing the width of the slot 2 and forcingapart the edges of the slot in the piston. As the portions of the pistonskirt adjacent the slot are-anchored to the webs W (Figure 2) thisexpansion of the slot will cause the portions A and B of the piston (seeFigure 5) to swing outwardly about the points C and D (Figure 2) thusincreasing the transverse dimension of the piston skirt and forming anoval shaped piston which possesses all of the advantages of a pistonhaving a skirt originally ground to such form.

As is seen in Figure 2 I preferably shape the tapered sleeve I so thatthe portions of the sleeve immediately adjacent the lips 3 and 4 and theslot 2 do not contact with the surface of the .plug 5. Thus, when theexpanding device is in position and the piston skirt walls have beenexpanded the function of the slot in the skirt is not. destroyed as thewalls of the skirt are. still permitted a certain flexibility ofmovement due to the fact that the sleeve I does not engage the plug 5throughout its entire circumference.

5 In Figure 10, which is a cross sectional view similar to Figure 2, butillustrating a slightly different embodiment of my expander, the sleevemember is of an oval cross section and engages the plug 5, which ispreferably of circular cross section, at the sides I1 and I8 thereof butis spaced from the plug member on what we may call the front l9 and theback portion 20 thereof. This arrangement providesfor asomewhat moreflexible'movement than does the arrangement of Figure 2 but it will beunderstood that the function of spacing the walls of 'the sleeve topermit the slot in the skirt of the piston to perform its intendedfunction after my expander device has been installed.

. In Figure 7 I have illustrated a modified form of my piston expanderin which the underside of A lock washer 9 may be inter- It will be seen.

the sleeve I and prevents relative rotation of the washer and sleeve.vThiswasher and serrated head surface gives a ratchet action uponrotation of the screw to expand the piston skirt and provides anindication of the degree of expansion given to the piston skirt as wellas preventing the loosening of the screw. A pin I3 is illustrated inFigure 7, this. pin extending out from the body of the plug 5 into theslot 2 of the sleeve I; This pin does not, however, extend beyond theedges of the lips 3 and 4 and serves merely to prevent relative rotationof the plug 5 and sleeve I thus insuring that the plug will be drawninto the sleeve upon rotation of the screw I in the proper direction.

3 and 4 at the large end of the sleeve I are preferably rounded off toprevent the hardened spring steel of the sleeve from digging into therelatively soft metal of the piston'and to facilitate the insertion ofthe device in the slot inthe piston skirt. The ends of the flanges orlips 3 and I at the small end of the sleeve I, however, have sharp edgeswhich are adapted to dig into the soft metal of the edges of the slot inthe piston and effectively prevent accidental removal'of the device. I I

In Figure 9 I have illustrated, in approximately full size, a modifiedform of my expanding device in which the plug member 5 is provided witha transversely extending lug or flange It at its large end. This flangeis adapted to engage the inner walls of the piston skirt when the deviceis installed and prevents the plug 5 from rotating within the sleeve I.When this flange I4 is used it will not be necessary to provide a pin l3as illustrated in Figure 4.

My complete expanding device weighs less than one-half ounce and I havefound that it does not materally change the balance of the piston or inany way affect the operation of the vehicle engine except to improve thefit of the piston in the cylinder. A single size of expanding device maybe used with a large range of sizes of pistons and my expanding devicecan be used to expand the pistons any amount within the usual practicallimits. 7

Although I have described in considerable detail the illustratedembodiments of my invention it will be seen by those skilled in the artthat variations and modifications may be made in the specific 'form ofmy piston expander without departing from the spirit of my invention. Ido not therefore wish to be limited to thespecific form described andillustrated, but claim as my invention all embodiments thereof comingwithin the scope of the appended claims.

I claim:

1. A piston skirt expander including a tapered sleeve'member having aslot extending lengthwise thereof, said sleeve having lip portionsadjacent saidslot adapted to engage the edges of a slot in the skirt ofa piston, a tapered plug fitting within said sleeve and means fordrawing said plug into said sleeve to vary the width of said slot insaid sleeve.

2, In a piston skirt expander, a tapered, resilient sleeve slottedlongitudinally and having piston engaging lips adjacent the slottherein, a

.ai m v.

piston engaging tapered plug member disposed within said sleeve andmeans for moving said plug longitudinally of said sleeve. I

. 3. In a piston skirt expander, a tapered sleeve slotted longitudinallyhaving piston engaging lips adjacent the slot therein and adjustablemeans acting longitudinally of the sleeve and engaging the same forvarying the distance between said lips.

4. In combination with a pistonhaving a slotted skirt, a skirt expanderdisposed in theslot and adapted to vary the width thereof, said expandercomprising aslotted sleeve member having lips removably engaging theedges of the slot in the piston and means for expanding the slot in saidsleeve whereby the width of the slot in the piston will be increased.

5. In a piston skirt expander, a'tapered, resilient sleeve slottedlongitudinally and having piston engaging lips adjacent the slottherein, a tapered plug extending into said sleeve, said pl having athreaded aperture extending thereinto, a screw having threadedengagement with siiid' plug in said aperture and .extending out of. thesmall endof said sleeve, said screw having an enlarged portion on theend which extends out of the sleeve, said enlarged portion being adaptedto engage the end of said sleeve whereby rotation of said screw in onedirection will draw said plug into said sleeve and expand the slottherein.

6. In a piston skirt expander, a tapered, resilient sleeve slottedlongitudinally and having piston engaging lips adjacent the slottherein, a tapered plugextending into said sleeve, said plug having athreaded aperture extending thereinto, a screw having threadedengagement with said a plug in said aperture and extending out of thesmall end of said sleeve, said screw having an 'enlarged portion on theend which extends out I tion of said screwjn one direction will drawsaid of the sleeve, said enlarged portion being adapted tocengage theend of said sleeve whereby rotaplug into said sleeve and expand theslottherein, and means-for locking said sleeve and plug against relativerotary movement.

7. In a piston skirt expander, a tapered, re silient sleeve slottedlongitudinallyand' having piston engaging lips adjacent the slottherein, a

1 plug' having ,a laterally extending 'lugon its large end [adapted toengage the wall of the piston skirt whereby relative rotary movement of'the plug and sleeve is prevented.

8,111 a piston expander, a tapered. resilient sleeve slottedlongitudinally and having A a lips adjacent the slot therein, a

tapered plug extending into said sleeve, said plug having a threadedaperture extending thereinto,

- a screw having threaded engagement with said plug in said aperture andextending out-of thesmall end of saidsleeve, said screw having anenlarged portion on the end which extends out of the sleeve, saidenlarged end being adapted to engage the end of said sleeve wherebyrotation of said screw in one direction will draw said plug into saidsleeve and expand the slot therein, and a pin extending from the surfaceof said plug into the slot in said sleeve whereby relative rotarymovement of said sleeve and plug will be prevented. i

9. Ina piston skirt expa'nder of the'type described, a resilient,slotted, tapered sleeve, a tapered plug disposed in said sleeve,saidplug being formed to engage the inner suface of said sleeve exceptadjacent the slot in said sleeve and means for moving said'plug intosaid sleeve. to expand said slot.

10. -In a piston skirt expander of the type described, a resilient,slotted, tapered, sleeve having lips adjacent the slot thereof adaptedto en-- gage the edges of the slot in the skirt of a piston, said lipshaving their ends adjacent the large end of the sleeve rounded off tofacilitate insertion of the expander lips into the piston skirt slot andhaving their opposite ends relatively sharp whereby to dig into themetal of the edges of the piston skirt slot and resist removal'of saidsleeve from said slot, and means coacting with said tapered sleeve'forvarying the distance between said lips.

.11. In an expanding device, a resilient slotted;

tapered sleeve, a tapered plug disposed in said sleeve, said plug beingshaped to engage the inner surface of said sleeve on areas extendinglengthwise of the sleeve on the sides thereof and to be spaced from thesleeve adjacent the slot therein and adjacent the portion of the sleeveopposite from said slot, and means for moving' said plug into saidsleeve to expand said slot.

12. In an expanding device, a resilient, slotted, tapered sleeve, a plugdisposed in said sleeve, said plug engaging the walls of said sleeve .onportions thereof and being spaced from the walls of thesleeve at otherportions thereof whereby the ed s of hue slot insaid sleeve may be movedtoward each other whensaid plug is in position in the sleeve.

1a...1nan expanding device, r resilient, slotted, tapered sleeve, a plugdisposed in said sleeve,

said plug engaging the walls of said sleeve on portions thereof andbeing spaced from .the walls of the sleeve at other portions thereofwhereby the edges ofthe'slot in said sleeve may be moved.

toward each other when said plug is in position in the sleeve,and'ineans for moving said plug 7 into said tapered sleeve to vary thewi'dth of the slot in said sleeve.

